In previous cases, which offer similar observations, the system supplies were not able to manage the elevated peak current demand in the ADIS16375 (1.5A, ~200us) during the start-up process. In these particular cases, the resulting voltage drop violated the operating conditions and causes a "failure to start." In comparison, the ADIS16485 only has a peak current of 650mA, but it does last longer (~1.75ms).

In previous cases, which offer similar observations, the system supplies were not able to manage the elevated peak current demand in the ADIS16375 (1.5A, ~200us) during the start-up process. In these particular cases, the resulting voltage drop violated the operating conditions and causes a "failure to start." In comparison, the ADIS16485 only has a peak current of 650mA, but it does last longer (~1.75ms).

I had one more idea on this. If the FNCIO_CTRL[7] = 1 and there is no input clock to drive sampling, the outputs will never change. This doesn't seem likely, but I thought I would mention it, since that can also cause the outputs to not update. I hope that this helps and look forward to your response.